A lot of different factors come into play when asking this question; each skaters answer will be different to another’s. For example, if you have 2 skaters, one a 6 foot 200lbs (6 foot 15 stone) and the other a 5’6 160lbs (11 stone) who both skate 4 times a week, The larger skater will need to get their skates sharpened more frequently due to their size and weight, they ware away through their edges much quicker than the smaller skater. Also skater that a lot of stops and tricks will need to get the skates sharpened frequently (stopping and tricking ware away your edges quickly).
There is no (correct) rule of thumb that a skater can use to determine when they should visit their Pro Shop to have their Ice Hockey skates sharpened, a skater must! Learn how to feel it out from themselves, when your skates need to be sharpened, you’ll know! It will feel as though you have no “grip” or bite on the ice when cornering or stopping, as a result, you’ll find your skates slipping out of turns or stops (which can not only be dangerous, but also very embarrassing and annoying) once you begin to develop these symptoms, it’s a good idea to have your skates sharpened.